BY-PRODUCTS FROM BAGASSE

By D.F Day, G. Dequeiroz, C-H. Chung and M. Kim
Audubon Sugar Institute, LSU Agricultural Center, Baton Rouge, La., USA
dday@agctr.lsu.edu

Abstract

A biorefinery will have to produce a range of products, including ethanol, for economic viability. Any process for manufacturing ethanol from bagasse will also yield lignin fragments which contain aromatic compounds, and some cellobiose due to incomplete cellulose conversion. The pretreatment and hydrolysis methods dictate the actual compositions of these streams. An ethanol, organo-solv process, a singlet oxygen pretreatment and an ammonia explosion process were tested, not only for their ability to increase sugar availability for fermentation, but also for the “by-products” produced.
A range of monophenolic compounds derived from the lignin were detected, ranging from 30 mg to 100 mg of vanillin equivalent per gram of dry bagasse. The mono phenols produced by the various treatments were characterized using GC/MS. The compound with commercial value that turned up in all treatments was vanillin.
Typically, enzyme hydrolysis of ligno-cellulose produces primarily glucose and a small amount of cellobiose. Cellobiose in its own right is a potentially valuable product as a non-nutritive sugar. Co-production of a b-glucosidase inhibitor, gluconic acid, during enzymatic hydrolysis of cellulose altered the amounts of glucose and cellobiose produced. Addition of a b-glucosidase inhibitor, gluconolactone or gluconic acid, significantly increased the amount of cellobiose with a corresponding decrease in amount of glucose produced. In situ production of cellobiose during enzymatic conversion, using the enzyme glucose oxidase, yielded the same effect. With a suitable concentration of glucose oxidase it was possible to convert over 19.3% of the cellulose to cellobiose.

KEYWORDS: biorefinery, by-products; mono-phenols, lignin

ISSCT XXVIth CONGRESS Durban, South Africa 29th July - 2nd August 2007) http://issct.intnet.mu/ComCop2007.htm.